“He has the chance to be at the heart of this club for the next decade and beyond,” said Mourinho.

“Paul is one of the best players in the world and will be a key part of the United team I want to build here for the future. He is quick, strong, scores goals and reads the game better than many players much older than he is.”

Pogba made just seven appearances during his previous spell at the club as a teenager, but returns as one of the world’s most famous players after winning four consecutive Serie A titles and leading France to the Euro 2016 final.

“Thanks @juventusfc and all Juventini. Goodbye means nothing, it is the time we spent together that matters,” Pogba posted on his official Twitter account.

It is the first time since now Real Madrid coach Zinedine Zidane joined the Spanish giants as a player in 2000 from Juventus that Madrid haven’t got their hands on the world’s most expensive player having also bagged Cristiano Ronaldo from United in 2009 for a record fee.

United brought the long-running transfer saga to an end in the early hours of the morning UK time.

The reported fee does not include agent’s fees. The transfer had stalled for weeks over how the two clubs would share the sizeable payout to Pogba’s representative Mino Raiola.

And the huge cash outlay will lead to questions over how Ferguson allowed Pogba to slip out of United’s hands four years ago over differences with Raiola.

In his 2015 book ‘Leading’, Ferguson described his first meeting with Raiola as “a fiasco”.

“He and I were like oil and water,” Ferguson wrote.

“From then on, our goose was cooked because Raiola had been able to ingratiate himself with Paul and his family and the player signed with Juventus.”

Raiola, who also represents two of United’s other new signings, Armenian playmaker Henrikh Mkhitaryan and star Swedish striker Zlatan Ibrahimovic, is set to make millions from the deal.

Mourinho insisted United’s financial muscle should be a source of pride not embarrassment.

“When other people break records, I don’t think it’s a reason to be sad. I think it’s a reason to be proud with the dimension of a club that can do that and can attract players of this dimension.”

However, the Portuguese boss has hinted Pogba’s arrival will signal the end of United’s spending spree.

“Our fundamental market is 75 percent done,” he said during United’s pre-season tour of China.

“When we sign one midfield player that crucial work will be done.”

Mourinho’s reign got off to a successful start on Sunday as Ibrahimovic scored the winner in a 2-1 victory over Premier League champions Leicester City in the Community Shield.